On chip diversity antenna switch

ABSTRACT

An on chip diversity antenna switch includes a first switch, a second switch, a third switch, and a fourth switch. The first switch is operably coupled to a pin associated with a first antenna, to a transmit path and to receive a transmit receive (T/R) control signal. The second switch is operably coupled to the pin associated with the first antenna, to a receive path, and to receive the T/R control signal. The third switch is operably coupled to a pin associated with a second antenna, the transmit path, and to receive the T/R control signal. The fourth switch is operably coupled to the pin associated with the second antenna, to the receive path, and to receive the T/R control signal. Based on the T/R control signal, the first or second antenna is coupled to the transmit or receive path via a single switch.

This invention is claiming priority under 35 USC § 119(e) to aprovisionally filed patent application having the same title as thepresent patent application, a filing date of Apr. 25, 2003, and anapplication No. Ser. of 60/465,421.

BACKGROUND OF THE INVENTION

1. Technical Field of the Invention

This invention relates generally to wireless communications systems andmore particularly to wireless communication devices.

2. Description of Related Art

Communication systems are known to support wireless and wire linedcommunications between wireless and/or wire lined communication devices.Such communication systems range from national and/or internationalcellular telephone systems to the Internet to point-to-point in-homewireless networks. Each type of communication system is constructed, andhence operates, in accordance with one or more communication standards.For instance, wireless communication systems may operate in accordancewith one or more standards including, but not limited to, IEEE 802.11,Bluetooth, advanced mobile phone services (AMPS), digital AMPS, globalsystem for mobile communications (GSM), code division multiple access(CDMA), local multi-point distribution systems (LMDS),multi-channel-multi-point distribution systems (MMDS), and/or variationsthereof.

Depending on the type of wireless communication system, a wirelesscommunication device, such as a cellular telephone, two-way radio,personal digital assistant (PDA), personal computer (PC), laptopcomputer, home entertainment equipment, et cetera communicates directlyor indirectly with other wireless communication devices. For directcommunications (also known as point-to-point communications), theparticipating wireless communication devices tune their receivers andtransmitters to the same channel or channels (e.g., one of the pluralityof radio frequency (RF) carriers of the wireless communication system)and communicate over that channel(s). For indirect wirelesscommunications, each wireless communication device communicates directlywith an associated base station (e.g., for cellular services) and/or anassociated access point (e.g., for an in-home or in-building wirelessnetwork) via an assigned channel. To complete a communication connectionbetween the wireless communication devices, the associated base stationsand/or associated access points communicate with each other directly,via a system controller, via the public switch telephone network, viathe Internet, and/or via some other wide area network.

For each wireless communication device to participate in wirelesscommunications, it includes a built-in radio transceiver (i.e., receiverand transmitter) or is coupled to an associated radio transceiver (e.g.,a station for in-home and/or in-building wireless communicationnetworks, RF modem, etc.). As is known, the transmitter includes a datamodulation stage, one or more intermediate frequency stages, and a poweramplifier. The data modulation stage converts raw data into basebandsignals in accordance with a particular wireless communication standard.The one or more intermediate frequency stages mix the baseband signalswith one or more local oscillations to produce RF signals. The poweramplifier amplifies the RF signals prior to transmission via an antenna.

As is also known, the receiver is coupled to the antenna and includes alow noise amplifier, one or more intermediate frequency stages, afiltering stage, and a data recovery stage. The low noise amplifierreceives inbound RF signals via the antenna and amplifies then. The oneor more intermediate frequency stages mix the amplified RF signals withone or more local oscillations to convert the amplified RF signal intobaseband signals or intermediate frequency (IF) signals. The filteringstage filters the baseband signals or the IF signals to attenuateunwanted out of band signals to produce filtered signals. The datarecovery stage recovers raw data from the filtered signals in accordancewith the particular wireless communication standard.

Even though wireless communication devices include a transmitter andreceiver, they generally communicate in a half duplex manner, i.e. theyare either transmitting or receiving. As such, a wireless communicationdevice may include a single antenna structure, which may include oneantenna or a diversity antenna structure that is shared by the receiverand the transmitter of the device. To facilitate the sharing of theantenna structure, the wireless communication device includes at leastone transmit/receive (T/R) switch.

In general the T/R switch couples either the receiver path or thetransmitter path of the wireless communication device to the antennastructure. Since the T/R switch is coupling radio frequency (RF) signalsin the megahertz to gigahertz range, the T/R switch must have a stablefrequency response over the frequency range of interest. As such, theT/R switch is generally an off chip device or is fabricated usinggallium arsenide integrated circuit process. Neither implementation isideal for a CMOS implemented radio frequency integrated circuit (RFIC).

Another issue with T/R switches is when used by a wireless communicationdevice that employs a diversity antenna structure. As is known, adiversity antenna structure includes two or more antennas that arephysically separated (e.g. by a quarter wave length, half wave length,or full wave length) but receive the same signal. The antenna thatreceives the signal with the largest signal strength is selected for useby the wireless communication device. For a two antenna diversitystructure, the wireless communication device includes two transmitreceive switches: one to select the transmit or receive path and theother to select the first or second antenna. In this instance, since theRF signals are traversing two T/R switches, the T/R switches need to beextra clean (i.e. have a flat frequency response over the frequencyrange of interest and induce very little noise) making it essential touse off chip T/R switches or gallium arsenide integrated circuit T/Rswitches in conjunction with a CMOS radio frequency integrated circuit,which dramatically adds to the cost of a radio frequency integratedcircuit.

Therefore, a need exists for an on chip implementation of a transmitreceive switch that provides clean RF switching for single or diversityantenna structures.

BRIEF SUMMARY OF THE INVENTION

The on chip diversity antenna switch of the present inventionsubstantially meets these needs and others. In one embodiment, the onchip diversity antenna switch includes a first switch, a second switch,a third switch, and a fourth switch. The first switch is operablycoupled to a pin associated with a first antenna, to a transmit path andto receive a transmit receive (T/R) control signal. The second switch isoperably coupled to the pin associated with the first antenna, to areceive path, and to receive the T/R control signal. The third switch isoperably coupled to a pin associated with a second antenna, the transmitpath, and to receive the T/R control signal. The fourth switch isoperably coupled to the pin associated with the second antenna, to thereceive path, and to receive the T/R control signal. When the T/Rcontrol signal is in a first state the first switch is active to couplethe pin associated with the first antenna to the receive path. When theT/R control signal is in a second state, the second switch is active tocouple the receive path to the pin associated with the first antenna.When the T/R control signal is in a third state, the third switch isactive to couple the pin associated with the second antenna to thetransmit path. When the T/R control signal is in a fourth state, thefourth switch is active to couple the pin associated with the secondantenna to the transmit path. Accordingly, with such an on chipdiversity antenna, the coupling of multiple antennas to the transmit orreceive path traverses only a single switch thereby reducing the adverseeffects of traversing multiple switches.

In another embodiment, an on chip diversity antenna switch includes afirst means, a second means, a third means, and a fourth means. Thefirst means couples a pin associated with a first antenna to a transmitpath when a T/R control signal is in a first state. The second meanscouples the pin associated with a first antenna to a receive path when aT/R control signal is in a second state. The third means couples a pinassociated with a second antenna to a transmit path when a T/R controlsignal is in a third state. The fourth means couples a pin associatedwith a second antenna to the receive path when a T/R control signal isin a fourth state.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is a schematic block diagram of a wireless communication systemin accordance with the present invention;

FIG. 2 is a schematic block diagram of a wireless communication devicein accordance with the present invention;

FIG. 3 is a schematic block diagram of a T/R switch module in accordancewith the present invention; and

FIG. 4 is a schematic block diagram of an alternate T/R switch module inaccordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 is a schematic block diagram illustrating a communication system10 that includes a plurality of base stations and/or access points12–216, a plurality of wireless communication devices 18–32 and anetwork hardware component 34. The wireless communication devices 18–32may be laptop host computers 18 and 26, personal digital assistant hosts20 and 30, personal computer hosts 24 and 32 and/or cellular telephonehosts 22 and 28. The details of the wireless communication devices willbe described in greater detail with reference to FIG. 2.

The base stations or access points 12–16 are operably coupled to thenetwork hardware 34 via local area network connections 36, 38 and 40.The network hardware 34, which may be a router, switch, bridge, modem,system controller, et cetera provides a wide area network connection 42for the communication system 10. Each of the base stations or accesspoints 12–16 has an associated antenna or antenna array to communicatewith the wireless communication devices in its area. Typically, thewireless communication devices register with a particular base stationor access point 12–14 to receive services from the communication system10. For direct connections (i.e., point-to-point communications),wireless communication devices communicate directly via an allocatedchannel.

Typically, base stations are used for cellular telephone systems andlike-type systems, while access points are used for in-home orin-building wireless networks. Regardless of the particular type ofcommunication system, each wireless communication device includes abuilt-in radio and/or is coupled to a radio. The radio includes a highlylinear amplifier and/or programmable multi-stage amplifier as disclosedherein to enhance performance, reduce costs, reduce size, and/or enhancebroadband applications.

FIG. 2 is a schematic block diagram illustrating a wirelesscommunication device that includes the host device 18–32 and anassociated radio 60. For cellular telephone hosts, the radio 60 is abuilt-in component. For personal digital assistants hosts, laptop hosts,and/or personal computer hosts, the radio 60 may be built-in or anexternally coupled component.

As illustrated, the host device 18–32 includes a processing module 50,memory 52, radio interface 54, input interface 58 and output interface56. The processing module 50 and memory 52 execute the correspondinginstructions that are typically done by the host device. For example,for a cellular telephone host device, the processing module 50 performsthe corresponding communication functions in accordance with aparticular cellular telephone standard.

The radio interface 54 allows data to be received from and sent to theradio 60. For data received from the radio 60 (e.g., inbound data),the-radio interface 54 provides the data to the processing module 50 forfurther processing and/or routing to the output interface 56. The outputinterface 56 provides connectivity to an output display device such as adisplay, monitor, speakers, et cetera such that the received data may bedisplayed. The radio interface 54 also provides data from the processingmodule 50 to the radio 60. The processing module 50 may receive theoutbound data from an input device such as a keyboard, keypad,microphone, et cetera via the input interface 58 or generate the dataitself. For data received via the input interface 58, the processingmodule 50 may perform a corresponding host function on the data and/orroute it to the radio 60 via the radio interface 54.

Radio 60 includes a host interface 62, digital receiver processingmodule 64, an analog-to-digital converter 66, a filtering/attenuationmodule 68, an IF mixing down conversion stage 70, a receiver filter 71,a low noise amplifier 72, a transmitter/receiver switch 73, a localoscillation module 74, memory 75, a digital transmitter processingmodule 76, a digital-to-analog converter 78, a filtering/gain module 80,an IF mixing up conversion stage 82, a power amplifier 84, a transmitterfilter module 85, and antennas 86 and 87. The antennas 86 and 87 arephysically separated by a quarter wavelength, half wavelength, or fullwavelength to provide an antenna diversity structure for the wirelesscommunication device. The T/R switch module 73, as will be discussedwith reference to FIGS. 3 and 4, provides the coupling of the antennas86 and 87 to either the transmit path or the receive path of thewireless communication device.

The digital receiver processing module 64 and the digital transmitterprocessing module 76, in combination with operational instructionsstored in memory 75, execute digital receiver functions and digitaltransmitter functions, respectively. The digital receiver functionsinclude, but are not limited to, digital intermediate frequency tobaseband conversion, demodulation, constellation demapping, decoding,and/or descrambling. The digital transmitter functions include, but arenot limited to, scrambling, encoding, constellation mapping, modulation,and/or digital baseband to IF conversion. The digital receiver andtransmitter processing modules 64 and 76 may be implemented using ashared processing device, individual processing devices, or a pluralityof processing devices. Such a processing device may be a microprocessor,micro-controller, digital signal processor, microcomputer, centralprocessing unit, field programmable gate array, programmable logicdevice, state machine, logic circuitry, analog circuitry, digitalcircuitry, and/or any device that manipulates signals (analog and/ordigital) based on operational instructions. The memory 75 may be asingle memory device or a plurality of memory devices. Such a memorydevice may be a read-only memory, random access memory, volatile memory,non-volatile memory, static memory, dynamic memory, flash memory, and/orany device that stores digital information. Note that when theprocessing module 64 and/or 76 implements one or more of its functionsvia a state machine, analog circuitry, digital circuitry, and/or logiccircuitry, the memory storing the corresponding operational instructionsis embedded with the circuitry comprising the state machine, analogcircuitry, digital circuitry, and/or logic circuitry.

In operation, the radio 60 receives outbound data 94 from the hostdevice via the host interface 62. The host interface 62 routes theoutbound data 94 to the digital transmitter processing module 76, whichprocesses the outbound data 94 in accordance with a particular wirelesscommunication standard (e.g., IEEE 802.11a, IEEE 802.11b, Bluetooth, etcetera) to produce digital transmission formatted data 96. The digitaltransmission formatted data 96 will be a digital base-band signal or adigital low IF signal, where the low IF typically will be in thefrequency range of one hundred kilohertz to a few megahertz.

The digital-to-analog converter 78 converts the digital transmissionformatted data 96 from the digital domain to the analog domain. Thefiltering/gain module 80 filters and/or adjusts the gain of the analogsignal prior to providing it to the IF mixing stage 82. The IF mixingstage 82 directly converts the analog baseband or low IF signal into anRF signal based on a transmitter local oscillation 83 provided by localoscillation module 74, which may be implemented in accordance with theteachings of the present invention. The power amplifier 84 amplifies theRF signal to produce outbound RF signal 98, which is filtered by thetransmitter filter module 85. The antenna 86 transmits the outbound RFsignal 98 to a targeted device such as a base station, an access pointand/or another wireless communication device.

The radio 60 also receives an inbound RF signal 88 via the antenna 86,which was transmitted by a base station, an access point, or anotherwireless communication device. The antenna 86 provides the inbound RFsignal 88 to the receiver filter module 71 via the Tx/Rx switch 73,where the Rx filter 71 bandpass filters the inbound RF signal 88. The Rxfilter 71 provides the filtered RF signal to low noise amplifier 72,which amplifies the signal 88 to produce an amplified inbound RF signal.The low noise amplifier 72 provides the amplified inbound RF signal tothe IF mixing module 70, which directly converts the amplified inboundRF signal into an inbound low IF signal or baseband signal based on areceiver local oscillation 81 provided by local oscillation module 74,which may be implemented in accordance with the teachings of the presentinvention. The down conversion module 70 provides the inbound low IFsignal or baseband signal to the filtering/gain module 68. Thefiltering/gain module 68 filters and/or gains the inbound low IF signalor the inbound baseband signal to produce a filtered inbound signal.

The analog-to-digital converter 66 converts the filtered inbound signalfrom the analog domain to the digital domain to produce digitalreception formatted data 90. The digital receiver processing module 64decodes, descrambles, demaps, and/or demodulates the digital receptionformatted data 90 to recapture inbound data 92 in accordance with theparticular wireless communication standard being implemented by radio60. The host interface 62 provides the recaptured inbound data 92 to thehost device 18–32 via the radio interface 54.

As one of average skill in the art will appreciate, the wirelesscommunication device of FIG. 2 may be implemented using one or moreintegrated circuits. For example, the host device may be implemented onone integrated circuit, the digital receiver processing module 64, thedigital transmitter processing module 76 and memory 75 may beimplemented on a second integrated circuit, and the remaining componentsof the radio 60, less the antenna 86, may be implemented on a thirdintegrated circuit. As an alternate example, the radio 60 may beimplemented on a single integrated circuit. As yet another example, theprocessing module 50 of the host device and the digital receiver andtransmitter processing modules 64 and 76 may be a common processingdevice implemented on a single integrated circuit. Further, the memory52 and memory 75 may be implemented on a single integrated circuitand/or on the same integrated circuit as the common processing modulesof processing module 50 and the digital receiver and transmitterprocessing module 64 and 76.

FIG. 3 is a schematic block diagram of a T/R switch module 73 thatincludes four switching means S1 through S4 and at least two integratedcircuit paths (IC Pad) coupled to two antennas 86 and 87. Each of theswitching means S1−S4, which may be a switch, transistor, bidirectionalswitch, cross couple transistor, etc., is controlled in accordance withthe T/R control signal 102. As is further shown, S1 and S3 are coupledto the transmit filter module 85 of the transmit path and switchingmeans S2 and S4 are coupled to the receiver filter module 71 of thereceiver path. The coupling of switches S1 and S3 to the transmit filtermodule 85 and the coupling of S2 and S4 to the receiver filter module 71may be done via an integrated circuit pad or an internal integratedcircuit node.

In operation, as shown in the corresponding table, when the T/R controlsignal 102 is in a first state, switching means S1 is active to coupleantenna 86 to the transmit filter module 85. When the T/R control signal102 is in a second state, switching means S2 is active to couple antenna86 to the receive filter module 71. When the T/R control signal 102 isin a third state, the third switching means is active to couple thetransmit filter module 85 to the second antenna 87. When the T/R controlsignal 102 is in a fourth state, the fourth switching means S4 is activeto couple the receive filter module 71 to the second antenna 87. Withsuch an on-chip T/R switching module 73, diversity antennas may bereadily used by a wireless communication device and provide singleswitch coupling between the antenna and the corresponding transmit pathor receive path.

If the switching means S1 through S4 are implemented utilizingtransistors, transistors may be implemented on chip utilizing galliumarsenide process such that the parasitic components of the transistorshave negligible impact on the RF signals traversing the transistors.Such operating frequencies may be in the range of a few hundredmegahertz to multiple gigahertz. It, however, the switching means S1through S4 are implemented utilizing transistors in a CMOS process theT/R switch module 73 may be implemented as shown in FIG. 4.

FIG. 4 illustrates the T/R switch module 73 to include transistorsT1–T4, integrated circuit paths coupled to antennas 86 and 87, and aparasitic compensation network 100. Each of the transistors T1–T4includes parasitic components such as parasitic capacitance, conductanceand/or resistance. In this illustration only the parasitic capacitancesare illustrated. To achieve a low on resistance for transistors T1–T4(e.g. approximately 2 ohms), a significant parasitic capacitance isestablished. If uncompensated, the parasitic capacitance at the RFfrequencies (a few hundred megahertz to multi gigahertz) wouldsubstantially attenuate the received RF signals and the transmitted RFsignals. To minimize the adverse effects of the parasitic capacitance,the parasitic compensation network 100 includes inductors L1–L4 and abias voltage circuit 104. The bias voltage circuit 104 generates a biasvoltage, which functions as an AC ground for inductors L1–L4. The biasvoltage may be established to correspond with a common mode voltage of adifferential signaling used within the wireless communication device.

The inductance of each inductor L1–L4 is selected to resonate with twoparasitic capacitances. For instance, L1 is selected to resonate withthe parasitic capacitance produced by transistor T2 and T4, whileinductor L3 compensates for parasitic capacitance produced by T4 and T3.Accordingly, by selecting the inductance value in conjunction with theknown parasitic capacitance value, the inductor in combination with thecapacitor may resonate at the operating frequencies of the receiveand/or transmitted RF signals thereby substantially reducing theattenuation provided by the parasitic capacitance.

Accordingly, the transmit/receive switch module 73 FIG. 4 may beimplemented in CMOS technology on a radio frequency integrated circuitand provide single switching between the transmit and receive paths anddiversity antennas. By including the parasitic compensation network 100,the adverse effects of the parasitic components of CMOS implementedtransistors T1–T4 are substantially avoided.

The preceding discussion has presented a on chip diversity antennaswitch that may be implemented utilizing CMOS technology or otherintegrated circuit manufacturing technologies. By utilizing a singleswitching means between the transmit and receive paths and the diversityantennas, performance is enhanced over prior art techniques thatrequired multiple T/R switches. As one of average skill in the art willappreciate, other embodiments may be derived from the teaching of thepresent invention without deviating from the scope of the claims.

1. An on-chip diversity antenna switch comprises: a first switchoperably coupled to a first terminal associated with a first antennathat is to be utilized for both transmitting and receiving, in whichwhen the first switch is closed, the first switch operably couples thefirst antenna to a transmitter; a second switch operably coupled to thefirst terminal associated with the first antenna, in which when thesecond switch is closed, the second switch operably couples the firstantenna to a receiver; a third switch operably coupled to a secondterminal associated with a second antenna that is to be utilized forboth transmitting and receiving, in which when the third switch isclosed, the third switch operably couples the second antenna to thetransmitter; and a fourth switch operably coupled to the second terminalassociated with the second antenna, in which when the fourth switch isclosed, the fourth switch operably couples the second antenna to thereceiver, wherein a transmit/receive (T/R) control signal coupled to allfour switches is used to close only one switch at a given time to selectbetween the first and second antennas to be coupled to either thetransmitter or the receiver to provide T/R control of two diversityantennas used for transmitting and receiving.
 2. The on-chip diversityantenna switch of claim 1, wherein switching function of each of thefirst, second, third, and fourth switches is performed by a transistor.3. The on-chip diversity antenna switch of claim 2 further comprises aparasitic compensation circuit operably coupled to compensate foradverse affects induced by parasitics of the transistors.
 4. The on-chipdiversity antenna switch of claim 3, wherein the parasitic compensationcircuit further comprises: a first inductor operably coupled to thefirst terminal and to AC ground; a second inductor operably coupled tothe second terminal and to the AC ground; a third inductor operablycoupled to a common transmit path of the first and third switches and tothe AC ground; and a fourth inductor operably coupled to a commonreceive path of the second and fourth switches and to the AC ground. 5.The on-chip diversity antenna switch of claim 4 further comprises a biasvoltage circuit operably coupled to provide a bias voltage that, atoperating frequencies of the on-chip diversity antenna switch, functionsas the AC ground.
 6. An on-chip diversity antenna switch comprises:first means for coupling a first terminal associated with a firstantenna that is to be utilized for both transmitting and receiving, to atransmitter when the first means for coupling is closed; second meansfor coupling the first terminal associated with the first antenna to areceiver when the second means for coupling is closed; third means forcoupling a second terminal associated with a second antenna that is tobe utilized for both transmitting and receiving, to the transmitter whenthe third means for coupling is closed; and fourth means for couplingthe second terminal associated with the second antenna to the receiverwhen the fourth means for coupling is closed, wherein a transmit/receive(T/R) control signal coupled to all four means for coupling is used toclose only one means for coupling at a given time to select between thefirst and second antennas to be coupled to either the transmitter or thereceiver to provide T/R control of two diversity antennas used fortransmitting and receiving.
 7. The on-chip diversity antenna switch ofclaim 6, wherein switching function of at least one of the first,second, third, and fourth means for coupling is performed by atransistor.
 8. The on-chip diversity antenna switch of claim 7 furthercomprises a parasitic compensation circuit operably coupled tocompensate for adverse affects induced by parasitics of the transistors.9. The on-chip diversity antenna switch of claim 8, wherein theparasitic compensation circuit further comprises at least one of: afirst inductor operably coupled to the first terminal and to AC ground;a second inductor operably coupled to the second terminal and to the ACground; a third inductor operably coupled to a common path transmit pathof the first and third means for coupling and to the AC ground; and afourth inductor operably coupled to a common receive path of the secondand fourth means for coupling and to the AC ground.
 10. The on-chipdiversity antenna switch of claim 9 further comprises a bias voltagecircuit operably coupled to provide a bias voltage that, at operatingfrequencies of the on-chip diversity antenna switch, functions as the ACground.
 11. A radio frequency integrated circuit (RFIC) comprises:transmit section operably coupled to convert baseband data into outboundradio frequency (RF) signals based on a transmit local oscillation;receive section operably coupled to convert received RF signals intoinbound baseband data based on a receive local oscillation; andtransmit/receive switch operably coupled to the transmit section and thereceive section, wherein the transmit/receive switch includes: a firstswitch operably coupled to a first terminal associated with a firstantenna that is to be utilized for both transmitting and receiving, inwhich when the first switch is closed, the first switch operably couplesthe first antenna to the transmit section; a second switch operablycoupled to the first terminal associated with first antenna, in whichwhen the second switch is closed, the second switch operably couples thefirst antenna to the receive section; a third switch operably coupled toa second terminal associated with a second antenna, that is to beutilized for both transmitting and receiving, in which when the thirdswitch is closed, the third switch operably couples the second antennato the transmit section; and a fourth switch operably coupled to thesecond terminal associated with the second antenna, in which when thefourth switch is closed, the fourth switch operably couples the secondantenna to the receive section, wherein a transmit/receive (T/R) controlsignal coupled to all four switches is used to close only one switch ata given time to select between the first and second antennas to becoupled to either the transmit section or the receive section to provideT/R control of two diversity antennas used for transmitting andreceiving.
 12. The RFIC of claim 11, wherein switching function of eachof the first, second, third, and fourth switches is performed by atransistor.
 13. The RFIC of claim 12 further comprises a parasiticcompensation circuit operably coupled to compensate for adverse affectsinduced by parasitics of the transistors.
 14. The RFIC of claim 13,wherein the parasitic compensation circuit further comprises: a firstinductor operably coupled to the first terminal and to AC ground; asecond inductor operably coupled to the second terminal and to the ACground; a third inductor operably coupled to a common transmit path ofthe first and third switches and to the AC ground; and a fourth inductoroperably coupled to a common receive path of the second and fourthswitches and to the AC ground.
 15. The RFIC of claim 14 furthercomprises a bias voltage circuit operably coupled to provide a biasvoltage that, at operating frequencies of the diversity antennas,functions as the AC ground.
 16. A radio frequency integrated circuit(RFIC) comprises: transmit section operably coupled to convert basebanddata into outbound radio frequency (RF) signals based on a transmitlocal oscillation; receive section operably coupled to convert receivedRF signals into inbound baseband data based on a receive localoscillation; and transmit/receive switch operably coupled to thetransmit section and the receive section, wherein the transmit/receiveswitch includes: first means for coupling a first terminal associatedwith a first antenna that is to be utilized for both transmitting andreceiving, to the transmit section when the first means for coupling isclosed; second means for coupling the first terminal associated with thefirst antenna to the receive section when the second means for couplingis closed; third means for coupling a second terminal associated with asecond antenna that is to be utilized for both transmitting andreceiving, to the transmit section when the third means for coupling isclosed; and fourth means for coupling the second terminal associatedwith the second antenna to the receive section when the fourth means forcoupling is closed, wherein a transmit/receive (T/R) control signalcoupled to all four means for coupling is used to close only one meansfor coupling at a given time to select between the first and secondantennas to be coupled to either the transmit section or the receivesection to provide T/R control of two diversity antennas used fortransmitting and receiving.
 17. The RFIC of claim 16, wherein switchingfunction of at least one of the first, second, third, and fourth meansfor coupling is performed by a transistor.
 18. The RFIC of claim 17further comprises a parasitic compensation circuit operably coupled tocompensate for adverse affects induced by parasitics of the transistors.19. The RFIC of claim 18, wherein the parasitic compensation circuitfurther comprises at least one of: a first inductor operably coupled tothe first terminal and to AC ground; a second inductor operably coupledto the second terminal and to the AC ground; a third inductor operablycoupled to a common transmit path of the first and second means forcoupling and to the AC ground; and a fourth inductor operably coupled toa common receive path of the second and fourth means for coupling and tothe AC ground.
 20. The RFIC of claim 19 further comprises a bias voltagecircuit operably coupled to provide a bias voltage that, at operatingfrequencies of the diversity antennas, functions as the AC ground.